Typical radar systems use a single exciter or transmitter and a single receiver with the radar antenna. This helps to reduce cost and complexity. Radar performance metrics can be improved if multiple receivers and exciters are used, and also if these are positioned toward the antenna elements so as to reduce degradation due to cabling. For example, better clutter attenuation is performance can be achieved because of the de-correlation of phase noise attributable to active elements. Sub-arraying also becomes possible, thereby allowing multiple-target tracking. Improved dynamic range can be achieved by converting the received signal reflected from the target into digital form as close to the receive antenna as possible.
Calibration of the various portions of the antenna array, or more generally the radar system, may be necessary for best radar performance. This performance may include beam pointing accuracy and sidelobe levels. Calibration includes the measuring of the phase and amplitude characteristics of the transmit and receive paths or transmission lines associated with each antenna element, and applying correction factors or weights to the element paths or transmission lines to achieve the desired relative amplitude and phase tapers.
Improved radar systems are desired.